One hundred patients with rectal adenocarcinoma were examined preoperatively with rectal endosonography (ES) and 50 were also examined with computed tomography (CT). ES predicted mesorectal lymph node involvement with an accuracy of 83 per cent, sensitivity of 88 per cent, specificity of 79 per cent, positive predictive value of 78 per cent and negative predictive value of 89 per cent. CT in comparison had an accuracy of 57 per cent, sensitivity of 25 per cent, specificity of 91 per cent, positive predictive value of 75 per cent and negative predictive value of 53 per cent. No particular histological architectural feature could be identified as responsible for false positive diagnosis though nodal size was significantly larger in the true positive and false positive group when compared with the true negatives (P less than 0.001 and P less than 0.01 respectively).

Forty-four patients with primary rectal cancers and six patients with benign rectal lesions were examined pre-operatively digitally, with endorectal sonography (ELU) and also computed tomography (CT). Digital examination of the rectal cancers had an overall accuracy of 68 per cent and predicted invasion beyond the muscularis propria with a sensitivity of 68 per cent, specificity of 83 per cent, positive predictive value of 100 per cent and negative predictive value of 46 per cent. In comparison CT had an accuracy of 82 per cent, sensitivity of 86 per cent, specificity of 62 per cent, positive predictive value of 91 per cent and negative predictive value of 50 per cent. ELU was the most reliable indicator of local invasion in rectal cancer when compared with postoperative histopathology with an accuracy of 91 per cent, sensitivity of 94 per cent, specificity of 87 per cent, positive predictive value of 97 per cent and negative predictive value of 78 per cent.

With the increasing use of transrectal sonography, accurate preoperative staging of rectal cancer requires correct identification of the normal ultrasonographic appearances of the colon and rectum. Fifteen rectal and colonic specimens have been studied in vitro to define the normal anatomy. Five distinct ultrasonic layers have been identified; a first echogenic layer that corresponds to the mucosa, a second echopoor layer made up of mucosa and muscularis mucosae, a third echogenic layer that is submucosa, a fourth echopoor layer that is muscularis propria, and a fifth echogenic layer made up of serosa and perirectal fat.

Eighty-five patients treated surgically for rectal cancer have been followed up by conventional clinical examination, sigmoidoscopy, and endosonography. Local recurrence was diagnosed in 22 patients. Nineteen of these had either sigmoidoscopic or digital evidence of recurrence and three were diagnosed solely by endosonography. In all cases endosonography gave additional information on which to base management decisions. Routine use of endosonography should allow the detection of early recurrence in a larger number of patients.

A new method for staging local invasion in rectal cancer has been assessed. Thirty-eight patients with primary rectal cancers have been examined pre-operatively with endoluminal rectal ultrasound and results compared with histological analysis of resected specimens in 33 cases. Three patients who also underwent laparotomy but not resection had good evidence of both stage T3 (1) and T4 (2) disease. The coefficient of correlation between ultrasonic and histological staging was 0.93 (P less than 0.001). Invasion beyond the muscularis propria was predicted with a sensitivity of 96 per cent, specificity of 92 per cent and a predictive value of 96 per cent.

Our joint school, pre-operative educational session remains a very effective way of delivering content to patients regarding their surgery. Continuous auditing is paramount to its success and there is potential scope for web-based learning as an adjunct to this validated session.

Digital examination is the most commonly used method of assessing local invasion in rectal cancer, but it is highly subjective and accuracy is related to surgical experience. The use of transrectal ultrasound in the preoperative staging of rectal cancer has been assessed in 51 patients with histologically proven rectal cancers. Results showed a high degree of correlation when compared with postoperative histopathology (r = 0.91, P less than 0.001). Invasion beyond the muscularis propria was predicted with a sensitivity of 97%, specificity of 92% and predictive value of 97%.

The normal echographic pattern produced by the colon and rectum has been investigated in vitro. Five basic ultrasonic layers or interfaces have clearly been identified; a first echogenic layer produced by the mucosa, then an echopoor layer representing the mucosa and muscularis mucosae, an echogenic layer which was submucosa, echopoor layer which was muscularis propria and an echogenic layer which was either pararectal fat or serosa. The effectiveness of endoluminal ultrasound (ELU) in the pre-operative staging of rectal cancer has been assessed in a group of 67 patients who were also, where possible, graded by digital examination and in some cases computer aided tomography (CT) (33 patients). Digital examination had an overall accuracy of 50% and could predict invasion beyond or confinement to the rectal with an accuracy of 64%. ELU is a highly accurate method for staging local invasion and when compared to post-operative histopathology had an overall correlation coefficient of 0.88 (p less than 0.001) (Rank Spearman). Our overall accuracy was 91% and it could predict invasion beyond the muscularis propria with a sensitivity of 96%, specificity of 94% and positive predictive value of 98%. In the cohort studied by both radiological techniques ELU was more accurate than CT where overall accuracy was 79%, sensitivity was 84%, specificity was 63% and the positive predictive value was 88%.